Provide MongoDb bulk write single operation and sink

[paualarco]

Additionally, it would be good if we could reuse the ReplaceOneModel and UpdateOneModel from the sink signatures,
where currently they are expecting a Tuple2[Bson, Bson] for the updates, and a Tuple2[Bson, Document], we could create a case class respectively to wrap those values in a more idiomatic way.
i.e

case class ReplaceOne[Doc](filter: Bson, replacement: Doc) {
 def toJava(options: ReplaceOptions) = ???
}